The present invention relates to an indicator circuit for digital signal cross-connect (DSX) bays, and, more particularly, to an indicator circuit for indicating to a technician in which bay to find a flashing tracer lamp indicator.
A digital cross-connect system (DSX) provides a location for interconnecting two digital transmission paths. The apparatus for a DSX is located in one or more frames, generally referred to as bays, usually in a telephone central office. The DSX apparatus also provides jack access to the transmission paths to trace a transmission path through the DSX.
DSX jacks are well known and typically include a plurality of bores sized for receiving plugs. U.S. Pat. No. 5,170,327, assigned to the present assignee, describes such a jack. The jacks are typically electrically connected to digital transmission lines, and are also electrically connected to a plurality of wire termination members used to cross-connect the jacks. By inserting plugs within the bores of the jacks, signals transmitted through the jacks can be traced as is well known. If a technician wants to know what a particular piece of equipment is coupled to through the DSX, the technician would insert a plug into a monitor bore of the jack coupled to that particular piece of equipment and look for a flashing light located on a second jack which is coupled to an end piece of equipment, i.e., the cross-connected equipment. This allows the technician to trace the transmission path through the DSX and determine what equipments are coupled together.
Each tracer lamp is located on a particular shelf in a particular row of a particular bay. There are generally several bays in any communications office. Typically, the tracer lamp only flashes for about 45 seconds. In a small central office this may be enough time to give the technician to find the other end of the circuit. In larger central offices with many bays, however, this is not enough time since the technician is not directed to any particular bay and thus must check each one until he discovers the illuminated tracer lamp. In both cases, tracing a transmission path is time consuming and tedious.
U.S. Pat. No. 5,418,334 describes a relative position tracer lamp to indicate to a technician which shelf or rack to find the flashing tracer lamp indicator thereby reducing the technician""s search for the flashing tracer lamp. The particular implementation described in this patent, however, suffers from several disadvantages. First, the circuitry employed requires a separate DC power source which makes it undesirable in a central office environment in which xe2x88x9248 volts is the available power supply. In addition, an intrusive technique, i.e., serial connection, is used to couple a transformer to a particular tracer wire thereby making it cumbersome to implement because of the direct wiring necessary.
Thus, it is desirable to provide a relative indicator that does not require its own power supply. In addition, it is desirable to provide a relative indicator that utilizes a non-intrusive method of detecting current change in a bay. Also, it is desirable to provide a relative indicator that reduces the overall effort and amount of wiring to be performed during installation.
According to a first aspect of the invention, there is provided a monitor circuit for indicating whether a digital signal cross-connect bay has a cross-connect jack that cross-connects equipment being tested. The circuit includes a sensor, a comparator, an indicator and a linear filter. The sensor has an input operatively coupled to a steady-state DC current carrying wire and detects a change in current flowing in the wire and generates an output signal at its output upon detection of a change. The comparator has an input operatively coupled to the output of the sensor and the comparator generates an output signal if the output of the sensor is above a predetermined level. The indicator is operatively coupled to the output of the comparator and the linear filter is coupled to a power supply that also supplies power to the cross-connect bay for powering the monitor circuit. The comparator sends a signal to the indicator if the sensor detects a current change in the power feed wire of the bay, causing the indicator to generate an indication.
According to a second aspect of the invention, there is provided a monitor circuit for indicating whether a digital signal cross-connect bay has a cross-connect jack that cross-connects equipment being tested. The circuit includes a comparator, an indicator and a linear filter. The comparator receives a signal output by a sensor that senses a change in current in a power feed wire of the bay. The indicator is operatively coupled to an output of the comparator and the linear filter is coupled to a power supply that also supplies power to the cross-connect bay for powering the monitor circuit. The comparator sends a signal to the indicator if the sensor detects a current change in the power feed wire of the bay causing the indicator to generate an indication.
According to a third aspect of the invention, there is provided a monitor circuit for indicating whether a digital signal cross-connect bay has a cross-connect jack that cross-connects equipment being tested. The circuit includes a balanced amplifier, a comparator and an indicator. The balanced amplifier receives a signal output by a sensor that senses a change in current in a power feed wire of the bay. The comparator is operatively coupled to an output of the balanced amplifier and the indicator is operatively coupled to an output of the comparator. The comparator sends a signal to the indicator if the sensor detects a current change in the power feed wire of the bay causing the indicator to generate an indication.